The process of transferring charged toner particles from an image bearing member marking device (e.g. photoreceptor) to an image support substrate (e.g., sheet) involves overcoming cohesive forces holding the toner particles to the image bearing member. The interface between the photoreceptor surface and image support substrate is not always optimal. Thus, problems may be caused in the transfer process when spaces or gaps exist between the developed image and the image support substrate. A critical aspect of the transfer process is focused on the application and maintenance of high intensity electrostatic fields in the transfer region for overcoming the cohesive forces acting on the toner particles as they rest on the photoreceptive member. Careful control of these electrostatic fields and other forces is required to induce the physical detachment and transfer-over of the charged toner particles without scattering or smearing the developer material. Mechanical devices that force the image support substrate into intimate and substantially uniform contact with the image bearing surface have been incorporated into transfer systems. Various contact blade arrangements have been proposed for sweeping the backside of the image support substrate, with a constant force, at the entrance to the transfer region. Xerographic systems use a transfer assist blade (TAB) to flatten print media onto the photoreceptor to ensure uniform transfer of the toner to the sheet.
A TAB is sometimes used to push the full width of paper sheet against the photoreceptor belt when transferring the toner image to the paper. TAB pressure uniformity along the width of the paper sheet can vary for a variety of reasons. Differing pressure uniformity across the paper width can produce various image artifacts and defects on the document. Currently, there is no automated method of determining TAB pressure uniformity along the width of a paper sheet while the TAB is installed in a machine.
One conventional approach for testing TAB pressure uniformity involves manually dusting the TAB with powdered toner so as to leave a print or “mark” on the backside of a sheet of paper. This enables service personnel to adjust timing.
However, when manually applying toner dust to a TAB, the results typically indicated non-uniform coverage and may provide only one marked sample sheet. Not having uniform toner along the width of the TAB and/or not having a population of marked sheets results in inaccurate and difficult diagnosis of problems.
There is an unmet need in the art for automated TAB timing calibration systems and methods that overcome the above-mentioned deficiencies and others.